Apparatus for dispensing liquid hydrocarbons



Ma 4,19 37. D MYON 2,079,027

APPARATUS FOR DISPENSING LIQUID HYDROCARBONS Filed July 26, 1955 5Sheets-Sheet l May 4, 1937.

D. MYON 2,079,027

APPARATUS FOR DISPENSING LIQUID HYDROCARBONS Filed July 26, 1955 5Sheets-Sheet 2- May 4, 1937. MYQN 2,079,027

APPARATUS FOR DISPENSING LIQUID HYDROCARBONS Filed July 26. 1955 5Sheets-She t a ay ,'1937. I D MYON 2,079,027

APPARATUS FOR DISPENSING LIQUID HYDROCAR BONS Filed July 26, 1955 5SheetsSheet 4 j e nfov Nv May 4, 1937. D. MYON 2,079,027

APPARA'i'US FOR DISPENSING LIQUID HYDROCARBONS Filed July 26, 1935 5Sheets-Sheet 5 Ihuen/nr o h Patented May 4, 1937 TENT OFFICE APPARATUSFOR DISPENSING LIQUID HYDROOARBONS Daniel Myon, Paris, France, assignorto Societe dEtude de Distributeurs Automatiques S. E.

D. A., Paris, France Application July 26, 1935, Serial No. 33,373 InFrance July 26, 1934 Claims.

This invention relates to improvements in the principle of operation andin the construction of apparatus for-dispensing liquid hydrocarbons, andmore particularly in those of these apparatus comprising two measuringvessels of the same capacity, alternately being filled up and emptied,in which the inversion of the function respectively fulfilled by saidvessels is obtained by utilizing the pressure of the liquid on the downside of the pump feeding the apparatus.

The invention more particularly refers, among apparatus of this type, tothose in which the distribution of the liquid, for filling up andemptying the measuring vessels, is ensured by coupled J slide valvesalternately putting each of said ves' sels in communication either withthe piping supplying the liquid under pressure, or with the dispensingpiping, these slide valves constituting a unit moving as a block andrigid, in its displacements, with two driving pistons which, accordingas the thrust of the liquid is exerted on one or the other of them,cause the displacement of the entire system in one direction or in theopposite direction.

, Finally, theinvention also consists in the use, in combination withnew devices producing new effects, of a known device by means of whichthe admission of the liquid under pressure, on either of thedrivingpistons of the system mentioned in the foregoing paragraph, isitself controlled by an auxiliary slide valve, or by a series'ofauxiliary slide valves, on the driving piston or pistons of which thethrust of the liquid under pressure is alternately exerted in onedirection or the other.

The invention is essentially characterized by the following points,which can be taken either separately, or in combination together or withother known devices:

1. The main and the auxiliary sets of slide valves operate in the samemanner, that is to say they each comprise, distinct or combined, twothree-way slide valves and two driving pistons operating in oppositedirections, these two sets of slide valves being hydraulically andreciprocally associated together, in such a manner that the displacementfrom end to end of one of the sets of slide valves causes, by reversalof the admission of fluid under pressure on the driving pistons of theother set, said other set to pass from the I 1 position it occupied tothe extreme opposed position. Both measuring vessels can be consideredas being respectively connected to the two pipe lines connecting each ofthe coupled slide valves of the main set to one of the driving pistonsof the auxiliary set.

2. The two systems of unbalancing springs (unsetting springs),respectively associated with each of the sets of double slide valves,according to a known arrangement such that alone the extreme positionsof the latter are positions of stable equilibrium, are adjustedrelatively to each other in such a manner that the minimum pressurenecessary for setting in action the auxiliary set of slide valves ismarkedly greater than the maximum pressure necessary for setting inaction the main set of associated slide valves.

7 3. The locking devices adapted, according to a known principle, toprevent premature inversions, or, more generally, untimely inversions ofthedispensing system, do not act directly on the main set of slidevalves, but temporarily prevent the displacements of the auxiliary setof slide valves. k

, In the accompanying drawings:

Fig. 1 diagrammatically illustrates, by way of example, a form ofcarrying the invention into practice.

Fig. 2 shows the main system in an intermediate position.

Fig. 3 illustrates a modification of the system of slide valves appliedto the main system.

Fig. 4 shows another modification applied to the auxiliary system.

Figs. 5, 6, 7 and 8 illustrate other forms of carrying the inventioninto practice.

The liquid to be dispensed, delivered bya feed pump (not shown), entersthe main set I of as sociated slide valves, through pipes 2 2 This mainset is, on the other hand, in communication, through pipes 3 3 withmeasuring vessels, Ili [6 and, simultaneously, as indicated later on,with the auxiliary set 2| of associated slide valves. Finally, the mainset also communicates, through a pipe 4, with the dispensing piping.

Ports are provided in the cylindrical body I opposite pipes 2, 2 theseports respectively causing this body to communicate with two upwardlyextending chambers 11*, Il in which a certain quantity of air alwaysremains trapped, these chambers acting, as indicated later on, as poweraccumulators during certain phases of the cycle of operation.

Two piston valves 5*, 5 and two driving pistons 6 6 move as a unit inthe cylindrical body. These four pistons are rigidly connected by anaxial rod 1. The intermediate portion of this rod is provided with a cammember 8, on which bears a roller 9. The roller 9 is supported in a forkor bracket H the stem of which ends in a flange I2 reciprocable in ahousing IE on the cylindrical body A spring I confined in the housingpresses against the flange and thus forces the roller 9 against the cam8.

The two driving pistons 6 6 respectively limit, at the ends of thecylindrical body two chambers l3", l3 into which open pipes M Mextending from the auxiliary system 2|.

The auxiliary system is similar to the main system and comprises acylindrical body 2| in which move two piston valves 25, 25 and twodriving pistons 26*, 26 rigidly connected by an axial rod 21. Into thecylindrical chamber 2| open two pipes 22 22 in direct communication,similarly to pipes 2 2 of the main system with the delivery side of thefeed pump. The pipe 24 serves to return the liquid either to the storagetank (not shown) of the plant, or to the suction side of the feed pump(not shown). Finally, pipes 23 23 are respectively in communication withthe pipes I4 Hi of the cylindrical body of the main system, whilst pipes34 34', leading to chambers 33 38 which chambers are delimited, at bothends of cylindrical body 2|, by the driving pistons 26, 26 Pipes 34 34communicate at the other end with the pipes 3 3 of the main system and,consequently, with the measuring vessels Ili I6".

Finally, a chamber [8 is provided into which the pipe 4 opens and fromwhich the hose l9 dispenses the measured liquid to the consumer. In thischamber |8 moves a float secured to one of the arms 36 of a bell crankrocking about a pivot pin 31, and the other arm 38 of which moves to theright for a purpose hereinafter set forth when the float is lifted. Therod 21 is provided midway of its length with a cam portion 28. A housingis formed on the cylinder 2|, opposite the cam 28 and within thishousing is a piston 32 on a rod 3| to the end of which adjacent the camis attached a roller 29 bearing on the piston and urging the same towardthe cam. The rod 3| extends into the chamber I8, passing through apacking gland in the wall of said chamber. The rod 3| and the arm 38 ofthe bell crank are so located that when the float is lifted, arm 38moves beneath the free end of rod 3| and prevents movement thereof, thuspreventing movement of the pistons in the cylinder 2|.

The whole is furthermore characterized by the fact that the respectiveadjustment of the springs Ill and 30 is such that the pressure necessaryfor compelling the roller 29 to ride up the incline of the cam 28 thusallowing movement of pistons Mi --26 is materially greater than thatwhich suflices for holding the roller 9 in engagement with cam 8.

The operation of this apparatus is as follows:

Both systems of slide valves being initially in the position shown inFig. l, the liquid delivered by the feed pump, through pipe 2 passesthrough the main system between the pistons 5 and 6 then it flows,through pipe 3*, into the measuring vessel lfi which it progressivelyfills up, this vessel being provided, according to a known principle,with a device allowing the air it contains to escape in the atmosphere,whilst preventing the issue of the liquid. As long as the vessel |6 isnot full, the pressure cannot increase therein, and cannot increaseeither in chamber 33 which is in permanent communication with thisvessel I6 As soon as the vessel 6 is full, the pressure of the liquid,which continues to be delivered by the feed pump, increases, until thethrust exerted by this liquid on piston 26 overcomes the thrust inreverse direction exerted by spring 30, through the medium of roller 29and cam 28, on the stem 21. The block of four associated pistons of theauxiliary system then begins to move towards the left and the liquidcontained in chamber 33 that flows towards a portion of the main system,delimited by pistons 5 and 5 which portion, being in communication withthe outlet pipe 4, cannot be under pressure at this moment.

The shape of the incline 28 being such that the thrust exerted towardsthe right by roller 29 first regularly diminishes when the set ofpistons of the auxiliary system slides towards the left, then becomesnil, then reverses, the stroke of said set of pistons, once initiated,takes place from end to end, so that it occupies the position indicatedin dotted lines in Fig. 1. In this position, the pistons and 26 delimit,in the cylindrical body 2|, an isolated chamber which puts pipe 22 incommunication with pipe 23''. The liquid under pressure delivered by thepump then flows, according to this path, towards chamber l3 in which thepressure increases until it is suflicient for overcoming theantagonistic thrust exerted by the spring |8, through the medium ofroller 9, on the incline 8. The set of four pistons 6 5 5 6 then movesas one block towards the right, and occupies the position indicated indotted lines in Fig. 1, whilst the liquid contained in chamber l3 flows,without back pressure through pipe M through the space delimited, in thecylindrical body 2 I, by the pistons 25* and 25 towards the return pipe24 stem 21 being at this time in the dotted line position of Fig. 1.

In the new position of the set of pistons of the main system, themeasuring vessel l6 previously filled up as above stated, is incommunication, through the space delimited, in the cylindrical body I,by the pistons 5 5 with the pipe 4 dispensing the liquid to theconsumer, and through which it is emptied, whilst the measuring vesselI6 is in communication, through the space delimited, in the cylindricalbody by pistons 6 and 5 with pipe 2 through which it is supplied withthe liquid delivered by the pump.

The parts are therefore at this moment, relatively to the vertical axisXX, in a position exactly symmetrical to that which has been consideredas the initial position, and the sequence of operations which has justbeen described is therefore repeated in an identical manner, but withinversion of the indicia a. and b appropriate to the various partsmentioned in this description.

Finally, it is to be noted that, during this second phase of theoperation, the liquid filling the measuring vessel 5 by flowing throughpipe 4, accumulates in chamber l8, before flowing to the exteriorthrough the hose l9, and lifts the float 29. During this movement, theupper end of the arm 38 of the bell crank comes opposite the lower endof the rod 3| of roller 29, preventing the latter from moving away forallowing the incline 28 to pass. Any sliding movement towards the rightof the set of pistons of the auxiliary system 2| is therefore preventedas long as the float remains lifted. The sections, lengths and levels ofthe hydraulic paths extending, on the one hand, from the measuringvessels to chamber l3 and, on the other hand, from this chamber to theend of the hose l9 dispensing the liquid to the consumer, are socomputed that it is impossible for the float to move down again as longas the measuring vessel I6 is not completely emptied. It resultstherefrom that, if the measuring vessel |6 should be completely filledup before the measuring vessel I6 is, entirely emptied, the thrustexerted by the liquid underpressure on piston 26 Whatever value it mayreach, could not cause the set of pistons of the auxiliary system tomove towards the right as long as float 20 by lowering has not allowedroller 29 to move away for permitting the incline 28 to pass.

The advantages of the device are the following:

1. The adjustment of the springs of the rollers i the hydraulic circuiton the down side of the pump, where air under pressure can be retained,

are always sufficient forensuring, not only the complete stroke of theset of pistons of the auxiliary system, but also that of the set ofpistons of the main system which succeeds to it without interval, evenif pumping was interrupted from the beginning of thestroke of the set ofpistons of the auxiliary system, or if the unsetting springs of bothsystems were not sufficient in themselves for ensuring the completion ofsaid strokes.

2. In any device where the pressure of the liquid delivered by thepumpis exerted, without relay, on the driving pistons of the main system,there occurs, as soon as the displacement of the system begins touncover theports putting the delivery side of the pump in communicationwith an empty measuring vessel, a very sudden drop of pressure owing tothe fact that theliquid under pressure flows towards this chamber. Thissuddenness of the drop of the driving pressure can be uid, and towardswhich the liquid delivered by the pump can flow only by compressingtheunsetting spring of the main system. It results therefrom thatbetween the moment, where, in its stroke, the

block of pistons of the auxiliary system begins to uncover theportsbetween which new communications will be established, and the momentwhere, these new communications having determined the setting inactionof the block of pistons of the main system, these latter pistons willbegin to uncover in their turn the ports which will be put incommunication by the displacement of said pistons, a certain interval oftime elapses during which the drop of pressure at the delivery side ofthe feed pump is insignificant, and during this time the pressure whichcontinues to be exerted on the driving piston of the auxiliary system,and which is added to the action of the unsetting spring of the system,determines the covering the ports but partially (Fig. 2), no perturbanceresults therefrom in the operation of the dispensing apparatus.

In fact, as soon as pumping is resumed for continuing the delivery ofliquid, or for effecting a new delivery, as the chamber W has remainedin communication with the delivery side of the pump, the liquid underpressure will again exert its action on the driving piston which, owingto the offset relation between both unsetting springs, will enter inaction under the influence ofthis pressure before the auxiliary systemhas been itself influenced by the latter, so that the block of slidevalves of the main system must entirely complete the stroke begun,before an inversion is possible.

Moreover, if the partial uncovering of the port of pipe 3 has allowedthe measuring vessel l6 to be emptied sufficiently slowly in order thatthe float 20 should not be lifted, no perturbance of the operation canresult therefrom, as the function of this float being only to preventthe movements of inversion of the auxiliary system, and the movements ofthe latter being possible only when there is at the delivery side of thepump a pressure sufficient for overcoming the resistance of theunsetting spring of said auxiliary system, it is obvious that beforethis minimum pressure has been reached, by putting the pump again inaction, a materially lower pressure will be attained which willdetermine the completion of the stroke device acting, not on thedisplacements of the.

main system, but on those of the secondary system, on which are exerted,owing to its much more reduced dimensions, resulting thrusts relativelysmall, mechanical actions proportionally much more efiicient areavailable, for given volume of the float, resulting inreduced risks ofwedging, shearing and various perturbances in the operation of thelocking device. I

Thus, in particular, instantaneous unlocking can be obtained when, thelevel of the liquid lowering in the intermediate chamber wherein movesthe float, the latter begins to move and to act by its weight on themechanism it controls. On the contrary, when the locking device acts, inthe known devices, directly on the main system of slide valves, theconsiderable thrusts to which this system is subjected cause seizingbetween both members, the coming in contact of which stops the operationof the mechanism, so that the driving action of the weight of the floatis insuflicient for disengaging these members: it is thereforenecessary, for unlocking to take place, to wait a certain period of timein order that, under the influence of the slight leakage alwaysoccurring in the delivery members, the driving hydraulic pressure issufliciently reduced on the driving piston for the wedged members todisengage from each other.

Many other forms of construction, in which the same eflect are obtainedby slightly different means, can be resorted to without departing fromthe scope of the invention, the main features above set forth beingpreserved.

Thus, each of the two systems (the main and auxiliary systems), or oneof them only, can be divided into two groups each composed of athree-way piston valve and of a driving piston, both groups beingmechanically associated together so that they always move with eachother.

The groups thus mechanically associated can be arranged either inalignment with each other (Fig. 3), or parallel to each other (Fig. 4),or according to any other relative setting.

In the form of construction illustrated in Fig. 3, the tipping device ofthe main system is slightly different from that described above; therigid rod 40 connecting both groups constituting the main system, isprovided with a slide 4| in which is fitted the end 42 of a link 43capable of pivoting about its other fixed end 44. To this link isattached, at 45, the tipping spring iii.

In the modification illustrated in Fig. 4 applied to the auxiliarysystem, another form of construction of the tipping and locking deviceis shown. Both groups of pistons are connected by a lever 46 capable ofrocking about the pivot 41 and on the arm 48 of which is attached, at49, the tipping spring 30 which always tends to restore it towardseither of its extreme positions.

A float 55, contained in chamber l8, carries a small bar 5! having, oneach of its branches 52 and 53, a notch, indicated at 54 and 55,respectively. When the float 50 is lifted by the presence of liquid inchamber I8, the notched bar 5| ensures the locking of the groups ofpistons of the auxiliary system. In either of the main and auxiliarysystems, or in both simultaneously, a group constituted by a pistonvalve and two driving pistons can be substituted for the group composedof two piston valves and two driving pistons. The connection of bothsystems necessitates certain inversions of the hydraulic paths and givesrise to four different combinations of the'whole, one of which is inaccordance with the form of construction illustrated in Fig. l, and theothers The tipping and locking device of the auxiliary system is thatshown in Fig. 4; the tipping device of the main system is thatillustrated in Fig. 3.

On the other hand, in each system of slide valves, the relativepositions of the pipes supplying and delivering liquid under pressurecan be inverted, the inlet pipe being at the center of the device, andthe delivery pipes being arranged near the ends.

Finally, the tipping spring can be constituted by any other means thanthat shown in Fig. l, as well as the locking device of the auxiliarysystem of slide valves. for both these devices, forms of constructiondeparting from that illustrated in Fig. 1.

What I claim as my invention and desire to secure by Letters Patent is:

1. Apparatus for dispensing liquids, more particularly liquidhydrocarbons, comprising two measuring vessels, a'liquid inlet pipeunder pressure, a delivery pipe, a first system or main system of slidevalves comprising two coupled piston slide valves adapted, according totheir position, to put the liquid inlet pipe under pressure incommunication with one or the other of the two measuring vessels and toput the measuring vessel, which is not in communication with the saidpipe, in communication with the delivery pipe, two driving pistonsdisplaceable in two driving chambers for varying the position of thepiston slide valves, a second system or auxiliary system of slide valvescomprising two coupled piston slide valves adapted according to theirposition Thus, in Fig. 4 are shown,

communication with one or the other of the I driving chambers of themain system.

2. Apparatus for dispensing liquids, more particularly liquidhydrocarbons, comprising two measuring vessels, a liquid inlet pipeunder pressure, a delivery pipe, a first system or main system of slidevalves comprising two piston slide valves mounted on a piston rod andadapted, according to their position, to put a liquid inlet pipe underpressure in communication with one or the other of the two measuringvessels and to put the measuring vessel, which is not in communicationwith the said pipe, in communication with the delivery pipe, two drivingpistons mounted on the said rod and displaceable in two driving chambersfor varying the position of the piston slide valves, a second system orauxiliary system of slide valves comprising two piston slide valvesmounted on a piston rod and adapted according to their position, to putthe said liquid inlet pipe in communication with one or the other of thedriving chambers of the main system, two driving pistons mounted on saidrod and displaceable in two driving chambers for varying the position ofthe piston slide valves, two pipes connecting the measuring vessels tothe said driving chambers of the auxiliary system, a liquid tank, areturn pipe leading to said tank adapted, according to the position ofthe piston slide valves of the auxiliary system, to be put incommunication with one or the other of the driving chambers of the mainsystem, an incline integral with the piston rod of the main system, aroller pressed against said incline by the action of a spring, a secondincline integral with the piston rod of the auxiliary system, a rollerpressed against said incline by the action of a spring which is strongerthan the corresponding spring of the main system.

3. Apparatus for dispensing liquids, more particularly liquidhydrocarbons, comprising two measuring vessels, a liquid inlet pipeunder pressure, a delivery pipe, a first or main system of slide valvescomprising two coupled piston slide valves adapted, according to theirposition, to put the liquid inlet pipe under pressure in communicationwith one or the other of the two measuring vessels and to put themeasuring vessel, which is not in communication with the said pipe, incommunication with the delivery pipe, two driving pistons displaceablein two driving chambers for varying the position of the piston slidevalves, a second or auxiliary system of slide valves comprising twocoupled piston slide valves adapted, according to their position, to putthe said liquid inlet pipe in communication with one or the other of thedriving chambers of the main system, two driving pistons for theauxiliary system displaceable in two driving chambers for varying theposition of the piston slide valves, two pipes connecting the measuringvessels to the said driving chambers of the auxiliary system, a returnpipe leading to the tank adapted, according to the position of thepiston slide valves of the auxiliary system, to be put in communica-2,079,027 'tion with one or the other of the driving chambers of themain system, means for resisting the displacement of the main system,means for resisting the displacement of the auxiliary system, so

constructed and arranged that the displacement ticularly liquidhydrocarbons, comprising two measuring vessels,a liquid inlet pipe underpressure, a delivery pipe, a first system or main system of slide valvescomprising two piston slide valves mounted on a piston rod and adapted,according to their position, to put the liquid inlet pipe under pressurein communication with one or the other of the two measuring vessels andto put the measuring vessel, which is not in communication with the saidpipe in communication with the delivery pipe, two driving pistonsmounted on the said rod and displaceable in two driving chambers forvarying the position of the piston slide valves, a second system orauxiliary system of slide-valvescomprising two piston slide valvesmounted on a piston rod and adapted, according to their position, to putthe said liquid inlet pipe in communication with one or the other of thedriving chambers of the main system, two driving pistons, mounted onsaid rod and displaceable in two driving chambers for varying theposition of the piston slide valves, two pipes connecting the measuringvessels to the said driving chambers of the auxiliary system, a liquidtank, a return pipe leading to said tank adapted, according to theposition of the piston slide valves ofthe'auxiliary system, to be put incommunication with one or theother of the driving 'chambers of the mainsystem, an incline integral with the piston rod of the main system, aroller pressed against said incline by the action of a spring, a secondincline integral with the piston rod of the auxiliary system, a rollerpressed against said incline by the action of a spring which is strongerthan the corresponding spring of the main system, a chamber interposedin the liquid delivery pipe, a float in said chamber, means forpreventing the displacement of the roller of the auxiliary system by thecorresponding incline when the said fioat is lifted.

5. Apparatus for dispensingliquids, more particularly liquidhydrocarbons, comprising two measuring vessels, a liquid inlet pipeunder pressure, a delivery pipe, a first system or main system of slidevalves, comprising two piston slide valves mounted on a piston rod andadapted, according to their position, to put the liquid inlet pipe underpressure in communication with one or the other of the measuringvessels, and to put the measuring vessel, which is not in communicationwith the said pipe, in communication with the delivery pipe, two drivingpistons mounted on the said rod and displaceable in two driving chambersfor varying the position of the piston slide valves, a, second system orauxiliary system 01' slide valves comprising two coupled piston slidevalves adapted, according to their position, to put the said liquidinlet valve in communication with one or the other of the drivingchambers of the main system, two driving pistons displaceable in twodriving chambers for varying the position of said piston slide valves,two pipes connecting the measuring vessels to the said driving chambersof the auxiliary system, a return pipe leading to the tank adapted,according to the position of the piston slide valve of the auxiliarysystem, to be put in communication with one or the other of the drivingchambers of the main system, means for resisting the displacement of themain system comprising an oblong eye formed in the piston rod, a crankthe end 'of which engages in said eye, a spring connected on they onehand to said crank and on the other hand to a fixed point perpendicularto the axis of rotation of the crank, means for resisting thedisplacement of the auxiliary system soconstructed and arranged that thedisplacement of the auxiliary system could only be effected for a,pressure of the inlet liquid higher than that which caused thedisplacement of the main system, an air accumulator connected to thehydraulic circuit.

6. Apparatus for dispensing liquids, more partic'ularly liquidhydrocarbons, comprising two measuring vessels, a tank, a liquid inletpipe under pressure, a delivery pipe, a first system or main system ofslide valves comprising two coupled piston slide valves adapted,according to their position, to put the liquid inlet pipe under pressurein communication with one or the other of the two measuring vessels andto put the meas uring vessel, which is not in communication with thesaid pipe, in communication with the delivery pipe, two driving pistonsdisplaceable in two driving chambers for varying the position of thepiston slide valves, a second system or auxiliary system of slide valvescomprising a first group formed by a piston slide valve and a drivingpiston for the displacement of said piston slide valve mounted on thesame piston rod, a second group formed by a piston slide valve and adriving piston for the displacement of said piston slide valve mountedon another piston rod parallel to the first one, a beam oscillatingabout a fixed axis in its center and pivoted to the ends of the twopiston rods, a pipe connected to the liquid inlet pipe and adapted,according to the position of the auxiliary system, to be put incommunication with one or the other of the driving chambers of the mainsystem, two pipes connecting the measuring vessels to the drivingchambers of the auxiliary system, a return pipe leading to the tankadapted, according to the position of the piston slide valves of theauxiliary system to be put in communication with one or the other of thedriving chambers of the main system.

7. Apparatus for dispensing liquids, more particularly liquidhydrocarbons, comprising two measuring vessels, a tank, a liquid inletpipe under pressure, a delivery pipe, a first system or main system ofslide valves comprising two coupled piston slide valves adapted,according to their position, to put the liquid inlet pipe under pressurein communication with one or the other of the two measuring vessels andto put the mealuring vessel, which is not'in communication with the saidpipe, in communication with the delivery pipe, two driving pistonsdisplaceable in two driving chambers for varying the position of thepiston slide valves, a second system or auxiliary system of slide valvescomprising on a common piston rod a piston slide valve and two drivingpistons displaceable in two driving chambers, a pipe connected to theliquid inlet pipe and put in communication, according to the position ofthe piston slide valve of the auxiliary system, with one or the other ofthe driving chambers of the main system, two pipes connecting themeasuring vessels to the driving chambers of the auxiliary system, tworeturn pipes leading to the tank adapted, according to the position ofthe piston slide valve of the auxiliary system, to be put incommunication with the driving chamber of the main system separated bythe piston. slide valve of the auxiliary system from the liquid inletpipe.

8. Apparatus for dispensing liquids, more particularly liquidhydrocarbons, comprising two measuring vessels, a tank, a liquid inletpipe under pressure, a delivery pipe, a first system or main system ofslide valves comprising, carried by one and the same piston rod, apiston slide valve and two driving pistons displaceable in two drivingchambers, the said piston slide valve adapted, according to the positionof the main system, to put the liquid inlet pipe in communication withone or the other of the measuring vessels and to put themeasuringvessel, which is not in communication with the said pipe, incommunication with the delivery pipe, a second system or auxiliarysystem of slide valves comprising two coupled piston slide valvesadapted, according to their position, to put the liquid inlet pipe incommunication with one or the other of the driving chambers of the mainsystem, two driving pistons displaceable in two driving chambers forvarying the position of the piston slide valves, two pipes connectingthe measuring vessels to the said driving chambers of the auxiliarysystem, a return pipe leading to the tank adapted, according to theposition of the piston slide valves of the auxiliary system, to be putin communication with one or the other of the driving chambers of themain system.

9. Apparatus for dispensing liquids, more particularly liquidhydrocarbons, comprising two measuring vessels, a liquid inlet pipeunder pressure, a delivery pipe, a tank, a first system or main systemof slide valves comprising, carried by one and the same piston rod, apiston slide valve and two driving pistons displaceable in two drivingchambers, the said piston slide valve adapted, according to the positionof the main system, to put the liquid inlet pipe in communication withone or the other of the measuring vessels and to put the measuringvessel, which is not in communication with the said pipe, incommunication with the delivery pipe, a second system or auxiliarysystem of slide valves comprising, mounted on a common piston rod, apiston slide valve and two driving pistons displaceable in two drivingchambers for varying the position of the said piston slide valve, a pipeconnected to the liquid inlet pipe and adapted, according to theposition of the piston slide valve of the auxiliary system, to be put incommuni cation with one or the other of the driving chambers of the mainsystem, two pipes connecting the measuring vessels to the drivingchambers of the auxiliary system, two return pipes leading to the tankadapted, according to the position of the piston slide valve of theauxiliary system, to be put in communication with the driving chamber ofthe main system separated by the piston slide valve of the auxiliarysystem from the liquid inlet pipe.

10. Apparatus for dispensing liquids, more particularly liquidhydrocarbons, comprising two measuring vessels, a tank, a liquid inletpipe under pressure, a delivery pipe, a first system or main system ofslide valves comprising two slide valves mounted on a piston rod andadapted, according to their position, to put the liquid inlet pipe incommunication with one or the other of the measuring vessels and to putthe measuring vessel, which is not in communication with the pipe, incommunication with the delivery pipe, two driving pistons mounted on thesaid rod and displaceable in two driving chambers for varying theposition of the piston slide valves, a second system or auxiliary systemof slide valves, comprising a first system formed by a piston slidevalve and a driving piston mounted on the same piston rod, a secondgroup formed by a piston slide valve and a driving piston for thedisplacement of said piston slide valve mounted on another piston rodparallel to the first one, a lever pivoted to the ended the two pistonrods, a pipe connected to the liquid inlet pipe and adapted, accordingto the position of the auxiliary system, to be put in communication withone or the other of the driving chambers of the main system, two pipesconnecting the measuring vessels to the driving chambers of theauxiliary system, a return pipe leading to the tank and adapted, ac-

cording to the position of the piston slide valve of the auxiliarysystem, to be put in'communication with one or the other of the drivingchambers of the main system, a chamber interposed in the liquid deliverypipe, a float in said chamber, means for resisting the displacement ofthe main system comprising an oblong eye formed in the piston rod ofthis system, a crank the end of which engages in the said eye, a springconnected on the one hand to said crank and on the other hand to a fixedpoint perpendicular to the axis of rotation of the crank, means forreslsting the displacement of the auxiliary system comprising an armintegral with the lever pivoted to the ends of the piston rods of saidsystem, a small bar carried by the float, two notches in said small baradapted, when the float is lifted, to form stops or abutments for theend of said arm, a spring connected to said arm, the fixed connectingpoint of which is arranged symmetrically with respect to the saidnotches, so that the displacement of the auxiliary system could only beeffected for a pressure of the inlet liquid higher than that whichcaused the displacement of the main system, and an air accumulatorconnected to the hydraulic circuit.

DANIEL MYON.

